Scientific and Technological Activities Commission


Terms of Reference

The AMS Committee on Planned and Inadvertent Weather Modification was established in 1968 to promote and guide the Society's contributions to the field of weather modification. This committee, in partnership with other STAC Committees, is responsible for promoting research, fostering the transfer of knowledge, and providing expertise on weather modification. The mandate of this committee includes both planned and inadvertent weather modification, as well as planned climate modification (geoengineering). Inadvertent climate modification is part of the mandate of the Climate Variability and Change committee.

The Committee is concerned with the processes by which weather at various scales is affected by planned and inadvertent introduction of aerosols into the atmosphere, and by changes in land use. More specifically, these include (the list is not exhaustive):

  1. Glaciogenic and hygroscopic cloud seeding for augmenting precipitation, hail suppression, and fog dispersal.
  2. Impacts of anthropogenic aerosols, such as smoke, air pollution and those of agricultural origins, on precipitation amounts and intensities, cloud electrification, hail storms, tornadoes, and tropical cyclones.
  3. Planned modification of severe convective storms and tropical cyclones by cloud seeding or manipulations of sea surface temperature.
  4. Impacts of land use changes, such as urbanization, deforestation, irrigation, dry land agriculture, afforestation, and grazing, on atmospheric processes (e.g., radiation, local circulations, and precipitation).
  5. Radiative and microphysical impacts of the atmospheric brown cloud on atmospheric heating, clouds, precipitation, and circulation systems such as monsoons.
  6. Seeding of marine stratocumulus for brightening the clouds to reflect more solar radiation back to space, as part of geoengineering.
  7. Dispersion of stratospheric aerosols for similar objectives of geoengineering.

In addition the Committee will address the ethical and societal concerns with respect to planned weather modification from cloud seeding for augmenting precipitation, to modification of severe storms and tropical cyclones, and to geoengineering.

Some of these issues may have some overlap with other committees, as there are no well- defined boundaries in the continuum of weather and climate and their anthropogenic modification. This will be addressed, for example, by coordination of joint sessions in conferences.

This committee carries out its mandate through the following activities:

  1. Organizing AMS-sponsored and co-sponsored conferences and conference sessions. In the past five years, we have organized the following activities:
    a. The 17th Conference on Planned and Inadvertent Weather Modification in Westminster, Colorado, in 21-25 April, 2008, jointly with the Weather Modification Association.
    b. The 18th Conference on Planned and Inadvertent Weather Modification, 24-27 January 2011, Seattle.
  2. Involvement in writing AMS Statements. Members of the committee have participated in the following recent statements:
    Inadvertent Weather Modification (Adopted by the AMS Council on 2 November 2010)
    Planned Weather Modification through Cloud Seeding (Adopted by the AMS Council on 2 November 2010)
    Geoengineering the Climate System (Adopted by the AMS Council on 20 July 2009)
  3. To advise the Society of current activities, trends, and prospects for planned and inadvertent weather modification and geoengineering by means of an annual report to the Society's Scientific and Technological Activities Commission.
  4. Stimulating interaction with other AMS committees, related professional societies, and national and international agencies.
  5. Nominating distinguished individuals to become Fellows and to receive awards of the Society.
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